Insects and other arthropods constitute over half of the living animal species on earth; they are important not only from a biological viewpoint but also as disease vectors and as agricultural, forest, and household pests. Insects interact chemically with one another, with plants, with hosts, and with predators. This project is concerned with elucidating these chemical interactions, which can influence both behavior and development. Among the arthropods to be studied are ticks, millipeds, centipeds, opilionids, aphids, beetles, lepidoptera, and termites. Some specific objectives include the characterization of (1) sex attractants and other pheromones of ixodid and argasid ticks, vectors of East Coast Fever and East African relapsing fever, (2) defensive compounds of a wide variety of arthropods, and (3) trail and alarm pheromones of termites. We plan to carry out syntheses of any new compounds encountered and to subject these compounds to screening for antibacterial, antifungal, antiviral, antihelminthic, and antitumor activity. The overall objectives of this work are (1) to increase our understanding of natural regulatory mechanisms well enough to provide the basis for novel control techniques for disease vectors and other anthropod pests and (2) to discover new natural products which may be useful in combatting disease.